Event Handling in a Radio Circuit

ABSTRACT

A radio circuit comprises an interface unit for communicating data and commands over a communication link between a digital baseband circuit and the radio circuit. Furthermore, the radio circuit comprises an event-scheduling unit, a local time-reference unit, a synchronization unit, and an execution-control unit. The event-scheduling unit is arranged to receive event-request commands specifying an event to be executed in the radio circuit and a time instant at which the specified event is to be executed, from the digital baseband circuit. Furthermore, the event-scheduling unit is arranged to, in response to receiving an event request-command, schedule the specified event to be executed on the specified time instant. The execution-control unit is arranged to issue execution of each scheduled event at the scheduled time instant based on time information from the local time reference unit. The local time-reference unit is synchronized with a time-reference unit in the digital baseband circuit in response to a synchronization command, from the synchronization unit.

TECHNICAL FIELD

The present invention relates to a radio circuit. More particularly, thepresent invention relates to event handling in a radio circuit.

BACKGROUND

Radio communication devices, such as mobile telephones and similarequipment, are becoming increasingly complex. Emerging communicationstandards, e.g. LTE (Long Term Evolution) and IMT (International MobileTelecommunication) advanced, will provide high data rates and be basedon complex techniques and algorithms to transmit and receive signals.For example, techniques used for efficient transmission, such asmodulation schemes, coding, channel estimation, synchronization etc.continue to grow in complexity with the evolution of standards. Theincreased complexity also applies to the radio circuitry that serves asan interface between the antenna and the digital baseband circuit, whichis hosting the algorithms for modulation, coding etc. For example, thecomplexity of the radio circuitry may increase due to an increasednumber of frequency bands and modes of operation that need to besupported. Hence, radio circuitry may need to be reconfigured based onmode of operation.

Furthermore, many parts of the radio circuitry are normally designed andoperated to cater for worst-case scenarios stipulated by standardspecifications. Such scenarios may be relatively rare or evennon-existent. Therefore, a more flexible radio circuit that can providejust enough performance at any given time may be advantageous e.g. inorder to save power. This would require an increased degree ofreconfigurability, resulting in a further increased complexity.

In order to facilitate such increased reconfigurability and flexibility,there is a need for a technique to facilitate time accurate control ofthe radio circuitry with respect to reconfiguration, data streams,calibration, debugging, etc. from the digital baseband circuit. US2006/0239337 discloses a method in a transceiver of receiving digitalcontrol information that includes both event and schedule informationfrom a baseband processor. The digital control information is stored ina storage of the transceiver, and the transceiver is operated accordingto the event and schedule information. To control the timing of theevents in the transceiver, the baseband processor supplies a strobesignal via a dedicated signal line to the transceiver. Scheduling theevents in relation to a strobe signal as disclosed in US 2006/0239337provides a relatively limited scheduling flexibility. Furthermore, theuse of the strobe signal adds to the complexity of the interfacecircuitry. For example, if the transceiver and the baseband processorreside on separate integrated circuits (ICs), dedicated pins for thestrobe signal are needed on the baseband processor IC and thetransceiver IC.

In view of the above, there is a need for improved circuitry for radiocommunication.

SUMMARY

Accordingly, an object of the present invention is to improve circuitryfor radio communication.

According to a first aspect, a radio circuit for operation with adigital baseband circuit is provided. The radio circuit comprises aninterface unit for communicating data and commands over a communicationlink between the digital baseband circuit and the radio circuit.Furthermore, the radio circuit comprises an event-scheduling unit. Theevent scheduling unit is arranged to receive event-request commands fromthe digital baseband circuit. Each event-request command specifies anevent to be executed in the radio circuit and a time instant at whichthe specified event is to be executed. Moreover, the event-schedulingunit is arranged to, in response to receiving an event request-command,schedule the specified event to be executed on the specified timeinstant.

In addition, the radio circuit comprises a local time-reference unit.The radio circuit further comprises a synchronization unit forsynchronizing the local time-reference unit with a time-reference unitin the digital baseband circuit in response to a synchronizationcommand. Furthermore, the radio circuit comprises an execution-controlunit arranged to issue execution of each scheduled event at thescheduled time instant based on time information from the local timereference unit.

The event-scheduling unit may be arranged to receive prioritizedevent-request commands from the digital baseband circuit. Eachprioritized event request command may specify a prioritized event to beexecuted in the radio circuit. The event-scheduling unit may further bearranged to, in response to receiving a prioritized event-requestcommand from the digital baseband circuit, schedule the specifiedprioritized event for immediate execution. Furthermore, theexecution-control unit may be arranged to issue immediate execution ofeach prioritized event scheduled for immediate execution.

The local time-reference unit may comprise a counter.

The synchronization unit may be arranged to set the local time-referenceunit to a specific time value indicated by the synchronization command.

The synchronization unit may be arranged to communicate a current timevalue of the local time-reference unit to the digital baseband circuitin response to the synchronization command.

The radio circuit may be arranged to receive a loop-back request commandfrom the digital baseband circuit. Furthermore, the radio circuit may bearranged to, in response to receiving a loop-back request command,immediately return a confirmation command to the digital basebandcircuit. Thereby, determination in the digital baseband circuit of alatency of the communication link between the digital baseband circuitand the radio circuit is facilitated.

The event-scheduling unit may comprise at least one event queue.Furthermore, for each of the at least one event queue, theevent-scheduling unit may comprise an event-handler unit adapted tostore events in the event queue sorted in an order of the time instantassociated with each event. The event-scheduling unit may furthercomprise a first-in/first-out memory operatively connected to theinterface unit for receiving event-request commands from the digitalbaseband circuit. Moreover, the event-scheduling unit may comprise anevent-dispatcher unit arranged to retrieve event-request commands fromthe first-in/first-out memory and, for each retrieved event-requestcommand, forward an event associated with the event-request command toone of the event handler units based on address information in theevent-request command.

The event-scheduling unit may be adapted to receive event-requestcommands comprising data associated with the event specified by theevent-request command.

A set of events that the radio circuit is adapted to execute maycomprises one or more of, but is not limited to a reconfiguration eventfor reconfiguring a hardware unit in the radio circuit, a measurementevent for measuring a state of a hardware unit in the radio circuit, ameasurement data receive event for receiving measurement data generatedduring a measurement event, a power-down event, a power-up event, asleep event, a wake-up event, a calibration event for calibrating ahardware unit in the radio circuit, a data-transmission event, a resetevent for restoring a setting of the radio circuit to a default setting,and a debugging event.

The radio circuit may be adapted to send event-request commands to thedigital baseband circuit for requesting events to be executed in thedigital baseband circuit.

According to a second aspect, a communication circuit is provided. Thecommunication circuit comprises a radio circuit according to the firstaspect. Furthermore, the communication circuit comprises a digitalbaseband circuit. The digital baseband circuit comprises a timereference unit and is adapted to issue and send event-request commandsto the radio circuit.

The digital baseband circuit in the communication circuit may bearranged to receive event-request commands from the radio circuit. Eachsuch event request command may specify an event to be executed in thedigital baseband circuit and a time instant at which the specified eventis to be executed. Furthermore, the digital baseband circuit in thecommunication circuit may be arranged to, in response to receiving anevent request-command, schedule the specified event to be executed onthe specified time instant. Moreover, the digital baseband circuit inthe communication circuit may be arranged to execute each scheduledevent at the scheduled time instant based on time information from thetime-reference unit of the digital baseband circuit.

According to a third aspect, an electronic apparatus is provided. Theelectronic apparatus comprises a radio circuit according to the firstaspect. The electronic apparatus may e.g. be, but is not limited to, anyof a portable radio communication equipment, a mobile radio terminal, amobile telephone, a communicator, an electronic organizer, a smartphone,and a computer.

According to a fourth aspect, a method of operating a radio circuit isprovided. According to the method, a local time-reference unit of theradio circuit is synchronized with a time-reference unit in a digitalbaseband circuit in response to a synchronization command. Furthermore,according to the method, event-request commands are received from thedigital baseband circuit. Each event-request command specifies an eventto be executed in the radio circuit and a time instant at which thespecified event is to be executed. Moreover, in response to receiving anevent request-command, the specified event is scheduled to be executedon the specified time instant. In addition, each scheduled event isexecuted at the scheduled time instant based on time information fromthe local time reference unit.

According to a fifth aspect, a computer program product comprisescomputer program code means for executing the method according to thefourth aspect, when said computer program code means are run by anelectronic device having computer capabilities.

According to a sixth aspect, a computer readable medium has storedthereon a computer program product comprising computer program codemeans for executing the method according to the fourth aspect, when saidcomputer program code means are run by an electronic device havingcomputer capabilities.

It is an advantage of embodiments of the invention that an improvedflexibility of scheduling events for execution in a radio circuit isfacilitated. For example, it is an advantage of some embodiments of theinvention that scheduling of events for execution relatively long aheadis facilitated. Moreover, it is an advantage of some embodiments of theinvention that event-request commands may be issued in an arbitraryorder, e.g. not necessarily in the same order as the events are to beexecuted in the radio circuit.

Further embodiments of the invention are defined in the dependentclaims.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps, or components, but does not preclude thepresence or addition of one or more other features, integers, steps,components, or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of embodiments of the inventionwill appear from the following detailed description, reference beingmade to the accompanying drawings, in which:

FIG. 1 illustrates schematically a mobile telephone in communicationwith a base station;

FIG. 2 is a block diagram of a communication circuit according to anembodiment of the invention;

FIG. 3 is a block diagram of a radio circuit according to an embodimentof the invention;

FIG. 4 is a block diagram of an event-scheduling unit according to anembodiment of the invention;

FIG. 5 is a block diagram of part of a digital baseband circuitaccording to an embodiment of the invention; and

FIGS. 6 a and b are flow charts for a method of operating a radiocircuit according to embodiments of the invention.

DETAILED DESCRIPTION

FIG. 1 illustrates an environment where embodiments of the presentinvention may be employed. An electronic apparatus 1 with radiocommunication capabilities is adapted to communicate with a base station(BS) 2 via radio signals. In FIG. 1, the electronic apparatus 1 isillustrated as a mobile telephone. However, this is only an example andnot intended to limit the scope of the present invention. For example,the electronic apparatus 1 may be, but is not limited to, a portableradio communication equipment, a mobile radio terminal, a communicator,i.e. an electronic organizer, a smartphone, or the like, or a personalcomputer (PC), e.g. a laptop. The electronic apparatus 1 may e.g. beadapted for radio communication in one or more types of communicationsystems, such as but not limited to one or more of GSM (Global Systemfor Mobile communication), UMTS (Universal Mobile TelecommunicationsSystem), LTE (Long Term Evolution), and IMT (International MobileTelecommunication) communication systems.

Furthermore, a single BS 2 is used as illustration in FIG. 1. However,this is only an example. The electronic apparatus 1 may be arranged tobe operatively connected to a plurality of BSs, operating within thesame type or different types of communication systems. For example, theelectronic apparatus 1 may be operatively connected to a plurality ofBSs in order to facilitate so called soft handover (SHO) between BSs.

FIG. 2 is a simplified block diagram of a communication circuit 5according to an embodiment of the invention. The communication circuit 5may e.g. be comprised in the electronic apparatus 1 (FIG. 1). Thecommunication circuit 5 may e.g. be a radio modem. According to theembodiment illustrated in FIG. 2, the communication circuit 5 comprisesa digital baseband circuit (DBB) 10. The DBB 10 has an I/O(Input/Output) port 12. Furthermore, according to the embodiment, theDBB 10 comprises a time-reference unit 14. The time reference unit 14may be used for providing a reference time for appropriate timing ofoccurrences of events in the communication circuit 5. According to someembodiments, the time reference unit 14 may comprise a counter, whiche.g. may be triggered by a positive or negative edge of a clock signalof the communication circuit. Hence, a counter value of the counter inthe time reference unit 14 may indicate the number of (positive ornegative) clock signal edges that have passed since the previous reset(or overflow) of the counter. Said counter value may be used as a valueof said reference time. The number of bits of the counter and thefrequency of the clock signal triggering the counter may e.g. be chosenbased on how accurately and how long ahead events need to be scheduledin time; the more accurately events need to be scheduled, the higher thefrequency, and the longer ahead events need to be scheduled, the morebits should be used in the counter. As a nonlimiting example, a clockfrequency of 19.5 MHz, which is 1/16 of the base frequency 312 MHz of aDigRF standard interface, may be used, whereby events may be scheduledwith a timing resolution of approximately 51.3 ns. According to e.g. the3GPP specifications, a radio frame may have a duration of 10 ms andcomprise 15 time slots. For a clock frequency of 19.5 MHz, an 18-bitcounter results in a counter value that repeats itself approximatelyevery 13.4 ms, and hence suffices to allow events to be scheduled inadvance to be executed at any time within a radio frame. Similarly,again for a clock frequency of 19.5 MHz, a 14-bit counter results in acounter value that repeats itself approximately every 840 μs, and hencesuffices to allow events to be scheduled in advance to be executed atany time within a time slot.

According to the embodiment illustrated in FIG. 2, the communicationcircuit 5 comprises a radio circuit 20. The radio circuit 20 has an I/Oport 22. As illustrated in FIG. 2, the I/O port 22 of the radio circuit20 may be arranged in operative connection with the I/O port 12 of theDBB 10, e.g. for communication of data and/or commands over acommunication link 30 between the DBB 10 and the radio circuit 20. Thecommunication link 30 may e.g. be, but is not limited to, acommunication link in accordance with the DigRF standard. Furthermore,according to the embodiment illustrated in FIG. 2, the radio circuit 20has an RF (Radio Frequency) port 24, adapted for connection to anantenna 35 for receiving and/or transmitting RF signals. Although asingle antenna is illustrated in FIG. 2, multiple antennas may well beused. For example separate transmit and receive antennas may be used.Furthermore, multiple antennas, e.g. arranged in a MIMO (Multiple InputMultiple Output) or similar antenna arrangement, may also be used forreceiving and/or transmitting RF signals.

Moreover, only a single radio circuit 20 and a single DBB 10 isillustrated in FIG. 2. However, this is only an example. More generally,the communication circuit 5 may comprise at least one DBB, each of whichmay be operatively connected to at least one radio circuit of thecommunication circuit 5 via communication links such as thecommunication link 30 in FIG. 2. For example, separate DBBs may beemployed for different types of communication systems. One or more ofthese DBBs may share the same radio circuit. Similarly, separate radiocircuits may e.g. be employed for different frequency bands etc.

FIG. 3 shows a block diagram of the radio circuit 20 according to anembodiment of the invention. According to this embodiment, the radiocircuit 20 comprises transmit and receive (Tx/Rx) circuitry 100 adaptedto be operatively connected to an antenna via the RF port 24 of theradio circuit 20 for receiving and/or transmitting RF signals. In FIG.3, examples of hardware units that may be comprised in the Tx/Rxcircuitry 100 are shown. As illustrated in FIG. 3, the Tx/Rx circuitry100 may comprise a transmit path and a receive path.

The transmit path may e.g. comprise a digital preprocessing unit 105.The digital preprocessing unit 105 may be arranged to perform varioussignal processing operations on digital signals, e.g. from the DBB 10.The various signal processing operations may e.g. include upsamplingand/or filtering. Furthermore, the transmit path may e.g. comprise adigital-to-analog converter (DAC) 110 for converting digital signals,e.g. from the digital preprocessing unit 105, into an analogrepresentation. The transmit path may further comprise a filter 115arranged to filter an output signal of the DAC 110, e.g. for bandwidthlimiting said output signal. Furthermore, the transmit path may comprisean upconversion mixer 120 for upconverting an output signal of thefilter 115 by mixing the output signal of the filter 115 with a localoscillator (LO) signal from a frequency synthesizer 125. Moreover thetransmit path may comprise a filter 130, e.g. for attenuation ofunwanted spectral images from an output signal of the upconversion mixer120. An output signal of the filter 130 may be fed to an input terminalof a power amplifier (PA) 135 with variable gain arranged to feed thesignal to be transmitted to the antenna 35 (FIG. 2). It may be necessaryto compensate for a nonlinear behavior of the PA 135 to reduce theamount of spurious signal components that may appear e.g. in adjacentchannels. Such compensation may e.g. be accomplished by means ofpredistortion. The predistortion may e.g. be performed in the digitaldomain. For example, the digital preprocessing unit 105 may be arrangedto perform predistortion operations. Alternatively, the predistortionmay be performed in the analog domain, e.g. by means of a dedicatedanalog predistortion unit (not shown in FIG. 3).

The receive path may comprise a low-noise amplifier (LNA) 140 withvariable gain for amplifying a received signal. Furthermore, the receivepath may comprise a filter 145 for removing out-of-band noise anddistortion from the output signal of the LNA 140. The output signal fromthe filter 145 may be fed to a downconversion mixer 150 arranged todownconvert the output signal from the filter 145 by mixing the outputsignal from the filter 145 with an LO signal from the frequencysynthesizer 125. An anti-aliasing filter 155 may be included in thereceive path for bandwidth limiting the output signal from the mixer150. Furthermore, the receive path may comprise an analog-to-digitalconverter (ADC) 160 for converting an output signal from theanti-aliasing filter 155 to a digital representation, e.g. for furtherprocessing in the DBB 10 (FIG. 2). Moreover, the receive path maycomprise a digital postprocessing unit 161. The digital postprocessingunit 161 may be arranged to perform various signal processing operationson digital signals output from the ADC 160. The various signalprocessing operations may e.g. include downsampling and/or filtering.

The Tx/Rx circuitry 100 illustrated in FIG. 3 is merely an example.Other types of Tx/Rx circuitry may be used as well in variousembodiments. For example, the transmit path may be arranged to performupconversion using more than one upconversion step via one or moreintermediate frequencies (IFs). Similarly, the receive path may bearranged to perform downconversion using more than one downconversionstep via one or more IFs. According to some embodiments, the digitalpreprocessing unit 105 and/or the digital postprocessing unit 161 may beomitted. Furthermore, the transmit and/or the receive path may bearranged for operation in quadrature using in-phase (I) and quadrature(Q) signal paths. Moreover, in FIG. 3, the transmit and receive pathsare operatively connected to the same RF terminal via a combiner circuit162. According to some embodiments, the transmit and receive paths maybe operatively connected to separate dedicated RF terminals.Modifications of the Tx/Rx circuitry 100 of FIG. 3 other than thoselisted in the foregoing may be made as well.

According to the embodiment illustrated in FIG. 3, the radio circuit 20comprises an interface unit 165. The interface unit 165 is arranged forcommunicating data and/or commands over the communication link 30between the DBB 10 and the radio circuit 20. The interface unit 165 maye.g. be, but is not limited to, an interface unit arranged to operate inaccordance with the DigRF standard.

Furthermore, according to the embodiment illustrated in FIG. 3, theradio circuit 20 comprises an event-scheduling unit 180. Theevent-scheduling unit 180 is arranged to receive event-request commandsfrom the DBB 10, e.g. via the interface unit 165. Each event-requestcommand specifies an event to be executed in the radio circuit 20 and atime instant at which the specified event is to be executed.Furthermore, the event-scheduling unit 180 is arranged to schedule theevent specified in an event-request command to be executed on thespecified time instant in response to receiving the event-requestcommand.

Moreover, according to the embodiment illustrated in FIG. 3, the radiocircuit 20 comprises a local time-reference unit 170. The localtime-reference unit 170 of the radio circuit 20 may be implemented inthe same or a similar way as the time-reference unit 14 of the DBB 10(FIG. 2). For example, according to some embodiments, the localtime-reference unit 170 may comprise a counter. Said counter may e.g. betriggered by a positive or negative edge of a signal, such as a clocksignal of the communication circuit 5. Hence, a counter value of thecounter in the local time-reference unit 170 may indicate the number of(positive or negative) clock signal edges that have passed since theprevious reset (or overflow) of the counter. Said counter value may beused as a reference-time value for accurate timing of events in theradio circuit 20.

According to the embodiment illustrated in FIG. 3, the radio circuit 20comprises a synchronization unit 175. The synchronization unit 175 isadapted to synchronize the local time-reference unit 170 with thetime-reference unit 14 in the DBB 10 in response to a synchronizationcommand. According to some embodiments, such a synchronization commandmay be issued by the DBB 10. Then, the synchronization unit 175 may e.g.be arranged to receive the synchronization command via the interfaceunit 165. Additionally or alternatively, the radio circuit 20 may beadapted to issue a synchronization command.

According to the embodiment illustrated in FIG. 3, the radio circuit 20comprises an execution-control unit 185. The execution control unit 185is arranged to issue execution of each event scheduled by the eventscheduling unit at the scheduled time instant based on time informationfrom the local time reference unit. Since the local time-reference unit170 can be synchronized with the time-reference unit 14 of the DBB 10(FIG. 2), the DBB 10 may efficiently and with accurate timing controlexecution of events in the radio circuit 20 by means of event-requestcommands. No dedicated strobe signal from the DBB 10 to the radiocircuit 20 is needed for timing events to be executed in the radiocircuit 20, which is an advantage. Furthermore, by appropriate design ofthe local time-reference unit 170 in the radio circuit and thetime-reference unit 14 in the DBB 10, e.g. by using a large enoughnumber of bits in counters comprised in these units, events can bescheduled well in advance. This may be advantageous if a large number ofevents should be scheduled to be executed simultaneously or almostsimultaneously. If a command, from the DBB 10 to the radio circuit 20,to schedule an event needs to be sent closely in time to when the eventshould be executed, the bandwidth of communication link 30 (FIG. 2),e.g. in terms of the number of commands that can be sent over thecommunication link 30 per unit time, may pose a bottleneck for thenumber of events that can be scheduled to be executed simultaneously oralmost simultaneously. Such a bandwidth problem can be alleviated ifevents can be scheduled well in advance. Moreover, since anevent-request command specifies the time instant when the event is to beexecuted by means of an absolute time value, i.e. not relative to apreceding event, a next strobe event, or the like, event requestcommands do not have to be sent in the same order as the correspondingevents are to be executed, which is an advantage e.g. in that itenhances flexibility.

The synchronization unit 175 may be arranged to synchronize the localtime-reference unit 170 of the radio circuit 20 with the time-referenceunit 14 in the DBB 10

(FIG. 2) in various different ways in various embodiments. In thefollowing, the reference time of the time-reference unit 14 is referredto as DBB time and the reference time of the local time-reference unit170 is referred to as radio time. According to some embodiments, thelocal time-reference unit 170 and the time-reference unit 14 may besynchronized in the sense that the DBB time and the radio time are setessentially equal. Thereby, the DBB 10 may issue an event-requestcommand specifying an event to be executed at a given time instantrepresented by a reference-time value in DBB time. The event-schedulingunit 180 may then schedule the event to be executed at a time instantrepresented by that same reference-time value, without modification, inradio time. According to some embodiments, setting the DBB time and theradio time essentially equal may be accomplished by setting thereference-time value of the local time-reference unit 170 equal to thecurrent reference-time value of the time-reference unit 14. According tosome embodiments, setting the DBB time and the radio time essentiallyequal may be accomplished by setting the reference-time value of thetime-reference unit 14 equal to the current reference-time value of thelocal time-reference unit 170. According to some embodiments, settingthe DBB time and the radio time essentially equal may be accomplished bysimultaneously setting the reference-time values of the localtime-reference unit 170 and the reference-time value of thetime-reference unit 14 equal to a predetermined value, e.g. bysimultaneously resetting the local time-reference unit 170 and the timereference unit 14.

According to some embodiments, the local time-reference unit 170 and thetime-reference unit 14 may be synchronized in the sense that the DBB 10is made aware of a time difference, or offset, between DBB time andradio time. For example, the synchronization unit may be adapted to, inresponse to a synchronization command, communicate a currentreference-time value of the local time-reference unit 170 to the DBB 10.Based on said current reference-time value of the local time-referenceunit 170, the DBB 10 may compute the offset between DBB time and radiotime. The DBB 10 may then compensate for the offset when issuing anevent-request command. For example, since the DBB 10 is aware of theoffset, it may issue an event-request command that specifies a timeinstant represented with a reference-time value in radio time.

According to some embodiments, the local time-reference unit 170 and thetime-reference unit 14 may be synchronized in the sense that the radiocircuit 20 is made aware of the offset between DBB time and radio time.For example, a synchronization command issued by the DBB 10 may includeinformation indicating a current reference-time value of thetime-reference unit 14. Based on said current reference-time value ofthe time-reference unit 14, the synchronization unit 175 may compute theoffset between DBB time and radio time. The radio circuit 20 may thencompensate for the offset when scheduling or executing events. Forexample, the DBB 10 may issue an event-request command that specifies atime instant represented with a reference-time value in DBB time. Theevent-scheduling unit 180 may then e.g. translate said reference-timevalue in DBB time to the corresponding reference-time value in radiotime based on the offset, and schedule the event specified in theevent-request command to be executed at a time instant represented withsaid corresponding reference-time value in radio time. Alternatively,the event-scheduling unit 180 may be adapted to schedule the event to beexecuted at a time instant represented with the reference-time value inDBB time. The execution-control unit 185 may then instead be arranged tocompensate for the offset by translating the reference-time value, withwhich the event has been scheduled by the scheduling unit 180, to thecorresponding reference-time value in radio time and use this translatedreference-time value for accurate timing control of execution of theevent.

According to some embodiments, the synchronization unit 175 may bearranged to set the reference-time value of the local time-referenceunit 170 to a specific time value indicated by a synchronization commandin response to the synchronization command. The specific time value maybe explicitly indicated by (e.g. included with) the synchronizationcommand. As a nonlimiting example, the specific time value may be acurrent reference-time value of the time-reference unit 14 in the DBB10. Alternatively, the specific time value may be implicitly indicatedby the synchronization command. As a nonlimiting example, thesynchronization command may be a command for resetting a counter in thelocal time-reference unit 170.

According to some embodiments, the timing-accuracy requirements are suchthat a latency of the communication link 30 (FIG. 2) between the DBB 10and the radio circuit 20 needs to be taken into account whensynchronizing the local time-reference unit 170 in the radio circuit 20with the time-reference unit 14 in the DBB 10. According to someembodiments, the latency is known in advance, e.g. from computersimulations during design of the communication circuit 5. According tosome embodiments, the latency may be determined based on measurements inthe communication circuit 5 during run time. For example, if the latencyin the communication link 30 between the DBB 10 and radio circuit 20 issymmetric, the latency can be measured by means of a loop-back requestcommand. The DBB 10 may send a loop-back request command to the radiocircuit 20. In response thereto, the radio circuit 20 may return aconfirmation command to the DBB 10. The difference between the time whenthe loop-back request command was sent and the time the confirmationcommand was received at the DBB 10 constitutes the total latency in thecommunication link 30. Half this value therefore represents the latencyin one direction. Hence, the loop-back request command facilitatesdetermination in the DBB 10 of the latency of the communication link 30.

The latency may e.g. be taken into account when issuing asynchronization command. For example, in an embodiment where the DBB 10is arranged to issue synchronization commands instructing thesynchronization unit 175 to set the reference-time value of the localtime-reference unit 170 in the radio circuit 20 equal to thereference-time value of the time-reference unit 14 in the DBB 10, theDBB 10 may add the latency to the current reference time value whensending the synchronization command and include the resulting sum in thesynchronization command. Hence, said sum represents the correct currentreference-time value of the time-reference unit 14 in the DBB 10 whenthe synchronization command is received by the radio circuit 20, wherebyaccurate synchronization of the local time-reference unit 170 in theradio circuit 20 and the time-reference unit 14 in the DBB 10 isfacilitated.

In an alternative embodiment, the latency may be known by the radiocircuit 20. For example, the latency may be communicated to the radiocircuit 20 from the DBB 10. Alternatively, the radio circuit 20 may beresponsible to measure the latency by sending a loop-back requestcommand to the DBB 10, which in response thereto returns a confirmationcommand to the radio circuit 20 for facilitating measurement of thelatency by the radio circuit 20. The latency may then be compensated forin the radio circuit 20, e.g. by the synchronization unit 175. Forexample, the synchronization unit 175 may be arranged to add the latencyto a reference-time value of the time-reference unit 14 included in asynchronization command from the DBB 10 to obtain the correct currentreference-time value of the time-reference unit 14 when thesynchronization command is received by the radio circuit 20.

The events that the radio circuit 20 is adapted to schedule and executein response to event-request commands from the DBB 10 may vary betweendifferent embodiments of the radio circuit 20. Some nonexhaustiveexamples of events that the radio circuit 20 may be adapted to executeare presented in the following.

Reconfiguration Events:

The radio circuit 20 may be adapted to schedule and executereconfiguration events. Examples of reconfiguration events are eventsfor reconfiguration of filters (e.g. filter 115, 130, 145 and/or 155 inFIG. 3), such as filter order, bandwidth, center frequency, etc. Otherexamples of reconfiguration events are events for reconfiguration ofoperating points for various hardware units in the Tx/Rx circuitry 100(FIG. 3), events for reconfiguration of the frequency synthesizer 125,e.g. for changing frequency. Yet other examples of reconfigurationevents include events for reconfiguration of an amplifier, such as theamplifiers 135 and 140 in FIG. 3, e.g. for changing gain or dynamicrange of the amplifier. Further examples of reconfiguration eventsinclude events for reconfiguration of a data converter, e.g. the DAC 110or the ADC 160 in FIG. 3, e.g. for changing sampling frequency,resolution, or, in the case of a ΔΣ ADC or DAC, for changing the orderof the ΔΣ ADC or DAC. Moreover, reconfiguration events may includeevents for reconfiguring the digital preprocessing unit 105 and or thedigital postprocessing unit 161, e.g. for changing sample-rateconversion factors for upsampling and/or downsampling.

Measurement Events:

The radio circuit 20 may be adapted to schedule and execute measurementevents. A measurement event may e.g. be an event for initiatingmeasurement of a state of a hardware unit in the Tx/Rx-circuitry 100.Such states may e.g. include a signal level (e.g. power or amplitude) atan input terminal or an output terminal of a filter or an amplifier,whether a ΔΣ ADC or DAC is close to saturation, etc. The radio circuit20 may e.g. comprise dedicated measurement units (not shown) adapted toperform such measurements. Furthermore, a measurement event may be anevent for collecting measurement results, e.g. from the measurementunits, and reporting the measurement results to the DBB 10.

Power Saving Events:

The radio circuit 20 may be adapted to schedule and execute power savingevents. Power saving events may e.g. include power-down and power-upevents, e.g. for turning off and on, respectively, a power-supplyvoltage of the whole or part of the Tx/Rx circuitry 100. Furthermore,power saving events may include sleep and wake-up events, e.g. fordisabling and enabling, respectively, one or more clock signalscontrolling hardware units in the Tx/Rx circuitry 100.

Calibration Events:

The radio circuit 20 may be adapted to schedule and execute calibrationevents. Calibration events may e.g. include events for calibration ofhardware units in the Tx/Rx circuitry 100 during run time. Examples ofhardware units that may be subject to calibration may include one ormore of filters, DACs, ADCs, and oscillators. Additionally oralternatively, calibration events may include calibration ofpredistortion settings (e.g. in the digital preprocessing unit 105 or adedicated analog predistortion unit).

Calibration events may additionally or alternatively include events forcoarse calibration of hardware units in the Tx/Rx circuitry 100 duringmanufacturing, e.g. for determining default calibration settings. Forsuch calibration during manufacturing, test signals may be generated inthe transmit path in the Tx/Rx circuitry 100 of the radio circuit 20 andinjected into the receive path in the Tx/Rx circuitry 100 of the sameradio circuit 20, e.g. either all the way via the antenna 35 or byclosing a switch (not shown) between an internal node in the transmitpath and an internal node in the receive path, for facilitating themanufacturing calibration. Thereby, the amount of external equipmentneeded for manufacturing calibration, e.g. measurement equipment,analyzer equipment, signal sources, etc., may be reduced. Utilizingembodiments of the present invention for efficient scheduling ofcalibration events during manufacturing may reduce the time required formanufacturing calibration.

Furthermore, calibration events may include events for resetting one ormore calibration settings of hardware units in the Tx/Rx circuitry 100to a default setting determined during manufacturing.

Data Transmission Events:

The radio circuit 20 may be adapted to schedule and execute eventsassociated with transmission of data. For example, an event-requestcommand may specify that a transmission of a particular set of datashould be started at a given time instant. The signal samplesrepresenting said set of data may e.g. be included with theevent-request command. Alternatively, the signal samples may betransferred from the DBB 10 to the radio circuit 20 separately from theevent request command and temporarily stored in a signal buffer unit(not shown in FIG. 3) of the radio circuit 20.

Debugging Events:

The radio circuit 20 may be adapted to schedule and execute eventsassociated with debugging. For example, debugging events may includereconfiguration of interconnection between hardware units in the radiocircuit 20, disabling and/or power off of hardware units in the radiocircuit 20, etc., in order to facilitate testing of individual hardwareunits or groups of hardware units in the radio circuit 20.

The DBB 10 may e.g. be adapted to select the time instant associatedwith some of the events listed above, e.g. reconfiguration and/orcalibration events, such that transmission of data is not interruptedand/or interfered with.

According to some embodiments, the DBB 10 may send commands to the radiocircuit 20 for requesting events to be executed in the radio circuitimmediately, or as soon as possible. Such events are in the followingreferred to as prioritized events and the commands for requestingprioritized events are referred to as prioritized event-requestcommands. Hence, according to some embodiments, the event-schedulingunit 180 is arranged to receive prioritized event-request commands thatspecify a prioritized event to be executed in the radio circuit 20 fromthe DBB 10. Furthermore, the event-scheduling unit may be adapted toschedule a prioritized event, which is specified in a prioritizedevent-request command, for immediate execution in response to receivingthe prioritized event-request command. Furthermore, theexecution-control unit 185 is arranged to issue immediate execution ofeach event scheduled for immediate execution. An example of aprioritized event-request command is the loop-back request commandmentioned above for facilitating latency measurements, in response towhich the event of returning a confirmation command to the DBB 10 isimmediately executed in the radio circuit 20.

FIG. 4 is a block diagram of the event-scheduling unit 180 according toan embodiment of the invention. According to the embodiment, the eventscheduling unit 180 comprises at least one event queue EQ1-EQN forstoring events to be executed. Events may e.g. be stored in an eventqueue EQ1-EQN in the form of an event identifier that identifies theevent to be executed and a time stamp indicating the time instant atwhich the event is to be executed. Furthermore, data associated with anevent may be stored along with the event in the event queue EQ1-EQN. Forexample, if the event is a configuration event, the associated data maybe configuration data, such as one or more parameter values. As anotherexample, if the event is a data transmission event, the associated datamay be data to be transmitted. According to some embodiments, dataassociated with an event may be comprised in an event-request command.Hence, according to some embodiments, the event-scheduling unit 180 maybe adapted to receive event-request commands comprising data associatedwith the event specified in the event-request command.

Furthermore, for each of the at least one event queue EQ1-EQN, theembodiment of the event-scheduling unit illustrated in FIG. 4 comprisesan event-handler unit EH1-EHN adapted to store events in the event queueEQ1-EQN sorted in an order of the time instant associated with eachevent. Each of the event handlers EH1-EHN may be operatively connectedto the execution-control unit 185 (FIG. 3) for communicating information(e.g. event identifier and time stamp) to the execution-control unit 185regarding the next event to be executed in the corresponding event queueEQ1-EQN, thereby enabling the execution-control unit 180 to issueexecution of the event at the scheduled time instant. Each event queueEQ1-EQN and corresponding event handler EH1-EHN may e.g. be assigned tohandle events relating to a specific hardware unit or group of hardwareunits, or to handle a specific type of event or group of events. Using aplurality of event queues may facilitate efficient simultaneousexecution of different events. For example, the execution-control unit185 (FIG. 3) may comprise a plurality of sub units (not shown). The subunits may be arranged to operate in parallel and each of the sub unitsmay be arranged to control the execution of events in a unique one ofthe plurality of event queues EQ1-EQN independently of the other subunits.

According to some embodiments, the radio circuit 20 may be adapted toreport errors and/or warnings to the DBB 10 over the communication link30. For example, the radio circuit 20 may be adapted to report one ormore of a calibration error, overflow in an event queue EQ1-EQN, anevent-time error (i.e. that a scheduled event could not be executed onthe specified time instant, e.g. due to a bug or a conflict with anotherevent), and a faulty or defect hardware unit to the DBB 10. Furthermore,the radio circuit 20 may be adapted to report status information to theDBB 10 over the communication link. For example, the radio circuit 20may be adapted to report that the execution of an event has beencompleted. Additionally or alternatively, the radio circuit 20 may beadapted to detect and report a change in an operating condition, such asbut not limited to a temperature change. In response thereto, the DBB 10may be adapted to take appropriate action, e.g. issue event-requestcommands to the radio circuit 20 for measurement events and/orcalibration events.

According to embodiments described so far in this specification, theevent-scheduling unit 180 and the execution-control unit 185 have beenillustrated as separate hardware units. However, according to someembodiments, the event-scheduling unit 180 and the execution-controlunit 185 may be merged. For example, the execution-control unit 185, orparts thereof, may be merged with the event handler units EH1-EHN in theevent-scheduling unit 180.

As illustrated in FIG. 1, the event-scheduling unit 180 may comprise afirst-in/first-out memory (FIFO) 200. The FIFO 200 may be operativelyconnected to the interface unit 165 for receiving event-request commandsfrom the DBB 10. Furthermore, the event-scheduling unit 180 may comprisean event-dispatcher unit 210. The event-dispatcher unit may be arrangedto retrieve event-request commands from the FIFO 200. Furthermore, theevent-dispatcher unit 210 may be arranged to, for each event-requestcommand retrieved from the FIFO 200, forward the event associated withthe event-request command to one of the event-handler units EH1-EHN forstorage in the associated event queue EQ1-EQN. For example, theevent-request command may comprise address information that enables theevent-dispatcher unit 210 to identify which of the event-handler unitsEH1-EHN that should be the recipient of the event. The addressinformation comprised in an event-request command may e.g. indicate ahardware unit or group of hardware units that the event is targeting,thereby facilitating for the event dispatcher unit 210 to forward theevent to the appropriate event handler unit EH1-EHN associated with saidhardware unit or group of hardware units.

FIG. 5 shows a block-diagram of part of the DBB 10 according to anembodiment of the invention. According to the embodiment, the DBB 10comprises an interface unit 300. The interface unit 300 is arranged forcommunicating data and/or commands over the communication link 30between the DBB 10 and the radio circuit 20. The interface unit 300 maye.g. be, but is not limited to, an interface unit arranged to operate inaccordance with the DigRF standard. Furthermore, the DBB 10 may comprisean event-request generation unit 310 for generating event-requestcommands to be sent to the radio circuit 10. Moreover, the DBB 10 maycomprise a FIFO 320 for temporary storage of event-request commands. Theevent-request generation unit 310 is adapted to send generatedevent-request commands to the FIFO 320 for temporary storage therein.The interface unit 300 is adapted to continuously read temporarilystored event-request commands from the FIFO 320 in accordance with atransmission rate of the interface unit 300 and forward theevent-request commands, over the communication link 30 (FIG. 2), to theradio circuit 20.

The radio circuit 20 may be adapted to request events to be executed inthe DBB 10. As a nonlimiting example, the radio circuit 20 may bearranged to detect a change in an operating condition, such as but notlimited to a temperature change. In response to detecting such a change,the radio circuit 20 may request that the DBB 10 takes appropriatemeasures to handle the change in operation condition. For example, theradio circuit 20 may request that the DBB 10 calculate one or more newparameter values for one or more settings of one or more hardware unitsin the radio circuit 20 based on the new operating condition andtransfer the new parameter values to the radio circuit 20 on a timeinstant specified in an event request command from the radio circuit 20to the DBB 10. Hence, the radio circuit 20 may be adapted to sendevent-request commands to the DBB 10 over the communication link 30. Forthat purpose, the radio circuit 20 may comprise one or more unitssimilar or identical to one or more units comprised in the DBB 10 inaccordance with the embodiment illustrated in FIG. 5. For example, theradio circuit 20 may comprise an event-request generation unit (notshown in FIG. 3), e.g. similar or identical to the event-requestgeneration unit 310 (FIG. 5) of the DBB 10, adapted to generateevent-request commands to be sent to the DBB 10. Furthermore, the radiocircuit 20 may comprise a FIFO (not shown in FIG. 3), e.g. similar oridentical to the FIFO 320 (FIG. 5) of the DBB 10, arranged totemporarily store event-request commands generated by the event-requestgeneration unit in the radio circuit 20. The interface unit 165 (FIG. 3)in the radio circuit 20 may be adapted to continuously read temporarilystored event-request commands from said FIFO in the radio circuit 20 inaccordance with a transmission rate of the interface unit 165 andforward the event-request commands, over the communication link 30 (FIG.2), to the DBB 10.

Similarly to event request commands sent from the DBB 10 to the radiocircuit 20, an event-request command sent from the radio circuit 20 tothe DBB 10 may specify an event to be executed in the DBB 10 and a timeinstant at which the specified event is to be executed. The DBB 10 maybe arranged to receive event-request commands from the radio circuit 20.Furthermore, the DBB 10 may be arranged to, in response to receiving anevent request-command, schedule the specified event to be executed onthe specified time instant. Moreover, the DBB 10 may be arranged toexecute each scheduled event at the scheduled time instant based on timeinformation from the time-reference unit 14 of the DBB 10. The DBB 10may e.g. comprise one or more units similar or identical to one or moreunits in embodiment of the radio circuit 20 illustrated in FIG. 3. Forexample, the DBB 10 may comprise an event-scheduling unit (not shown),e.g. similar or identical to the event-scheduling unit 180 (FIG. 3) ofthe radio circuit 20. The event-scheduling unit of the DBB 10 may bearranged to receive event-request commands from the radio circuit 20,e.g. via the interface unit 300 (FIG. 5). Furthermore, theevent-scheduling unit of the DBB 10 may be arranged to schedule theevent specified in an event-request command to be executed on thespecified time instant in response to receiving the event-requestcommand. Moreover, the DBB 10 may comprise an execution-control unit(not shown), e.g. similar or identical to the execution-control unit 185(FIG. 3) of the radio circuit 20. The execution control unit of the DBB10 may be arranged to issue execution of each event scheduled by theevent scheduling unit of the DBB 10 at the scheduled time instant basedon time information from the time reference unit 14 (FIG. 2) of the DBB10. Since the local time-reference unit 170 can be synchronized with thetime-reference unit 14 of the DBB 10 (FIG. 2), the radio circuit 20 mayefficiently and with accurate timing control execution of events in theDBB 10 by means of event-request commands.

According to some embodiments of the invention, a method of operatingthe radio circuit 20 is provided. The method comprises synchronizing thelocal time-reference unit 170 of the radio circuit 20 with thetime-reference unit 14 in the DBB 10 in response to a synchronizationcommand. Furthermore, the method comprises receiving event-requestcommands from the DBB 10. Each event request command may specify anevent to be executed in the radio circuit 20 and a time instant at whichthe specified event is to be executed. Moreover, the method maycomprise, in response to receiving an event-request command, schedulingthe specified event to be executed on the specified time instant. Themethod may further comprise executing each scheduled event at thescheduled time instant based on time information from the local timereference unit 170 in the radio circuit 20.

FIG. 6 a illustrates a flow chart for an embodiment of the method.According to this embodiment, it is checked in step 400 whether asynchronization command has been issued. If the answer in step 400 isyes, the local time reference unit 170 in the radio circuit 20 issynchronized with the time-reference unit 14 in the DBB 10 in step 410.Thereafter, the method proceeds to step 420. If the answer in step 400is no, the method proceeds directly to step 420.

In step 420, it is checked whether an event-request command has beenreceived from the DBB 10. If the answer in step 420 is yes, the eventspecified in the received event-request command is scheduled to beexecuted at the time instant specified in the event-request command instep 430. Thereafter, the method proceeds to step 440. If the answer instep 420 is no, the method proceeds directly to step 440.

In step 440, the current reference-time value of the localtime-reference unit 170 is compared with the time instants associatedwith scheduled events to determine whether there are any events thatshould be executed in the radio circuit 20 at the present time instant.If the answer in step 440 is yes, the event(s) to be executed at thepresent time instant is/are executed in step 450. Thereafter, the methodreturns to step 400. If the answer in step 440 is no, the method returnsdirectly to step 400.

FIG. 6 b illustrates a flow chart for another embodiment of the method.In addition to the steps illustrated in FIG. 6 a, the embodimentillustrated in FIG. 6 b comprises the steps 460 of detecting anevent-time error and 470 of handling a detected event-time error. Afterperforming step 450, or if the answer in step 440 is no, the methodproceeds to step 460, instead of returning to step 400 as in theembodiment illustrated in FIG. 6 a. In step 460, it is checked whetheran event-time error has occurred, e.g. if there is an event scheduled bythe event-scheduling unit 180 that could not be executed on thescheduled time instant. If the answer in step 460 is yes, the detectedevent-time error is handled in step 470, e.g. by reporting theevent-time error to the DBB 10. Thereafter, the method returns to step400. If the answer in step 460 is no, the method returns directly tostep 400. It is readily appreciated that, in some embodiments, more thanone event-time error may be detected in step 460, and more than oneevent-time error may be handled in step 470.

The flow charts illustrated in FIG. 6 a and b are only examples. Variousother steps may be included in other embodiments. Furthermore, the stepsillustrated in FIG. 6 a and b may be performed in a different order inother embodiments. Moreover, steps illustrated as being performedsequentially in FIG. 6 a and b may be performed in parallel in otherembodiments.

One or more of the units described above, e.g. one or more of the localtime-reference unit 170, the synchronization unit 175, theevent-scheduling unit 180, and the execution-control unit 185 may beimplemented with dedicated, application-specific hardware units.Additionally or alternatively, one or more of the units described above,e.g. one or more of the local time-reference unit 170, thesynchronization unit 175, the event-scheduling unit 180, and theexecution-control unit 185 may be implemented with programmable hardwareunits, such as one or more microprocessor, microcontroller, and/orfield-programmable gate array (FPGA), programmed and/or configured toperform the function of the units. Hence, embodiments of the inventionmay be embedded in a computer program product, which enablesimplementation of the method and functions described herein. Saidembodiments of the invention may be carried out when the computerprogram product is loaded and run in a system having computercapabilities. Computer program, software program, program product, orsoftware, in the present context mean any expression, in any programminglanguage, code or notation, of a set of instructions intended to cause asystem having a processing capability to perform a particular functiondirectly or after conversion to another language, code or notation.

The present invention has been described above with reference tospecific embodiments. However, other embodiments than the abovedescribed are possible within the scope of the invention. Differentmethod steps than those described above, performing the method byhardware or software, may be provided within the scope of the invention.The different features and steps of the invention may be combined inother combinations than those described. The scope of the invention isonly limited by the appended patent claims.

1. A radio circuit for operation with a digital baseband circuit,comprising: an interface unit for communicating data and commands over acommunication link between the digital baseband circuit and the radiocircuit; an event-scheduling unit arranged to: receive event-requestcommands, wherein each event-request command specifies an event to beexecuted in the radio circuit and a time instant at which the specifiedevent is to be executed, from the digital baseband circuit; and inresponse to receiving an event request-command, schedule the specifiedevent to be executed on the specified time instant; a localtime-reference unit; a synchronization unit adapted to synchronize thelocal time-reference unit with a time-reference unit in the digitalbaseband circuit in response to a synchronization command; and anexecution-control unit arranged to issue execution of each scheduledevent at the scheduled time instant based on time information from thelocal time reference unit.
 2. The radio circuit according to claim 1,wherein the event-scheduling unit is arranged to: receive prioritizedevent-request commands, wherein each prioritized event request commandspecifies a prioritized event to be executed in the radio circuit, fromthe digital baseband circuit; and in response to receiving a prioritizedevent-request command from the digital baseband circuit, schedule thespecified prioritized event for immediate execution; and theexecution-control unit is arranged to issue immediate execution of eachprioritized event scheduled for immediate execution.
 3. The radiocircuit according to claim 1, wherein the local time-reference unitcomprises a counter.
 4. The radio circuit according to claim 1, whereinthe synchronization unit is arranged to set the local time-referenceunit to a specific time value indicated by the synchronization command.5. The radio circuit according to claim 1, wherein the synchronizationunit is arranged to communicate a current time value of the localtime-reference unit to the digital baseband circuit in response to thesynchronization command.
 6. The radio circuit according to claim 1,wherein the radio circuit is arranged to receive a loop-back requestcommand from the digital baseband circuit and, in response thereto,immediately return a confirmation command to the digital basebandcircuit (10), thereby facilitating determination in the digital basebandcircuit of a latency of the communication link between the digitalbaseband circuit and the radio circuit.
 7. The radio circuit accordingto claim 1, wherein the event-scheduling unit comprises: at least oneevent queue; and for each of the at least one event queue, anevent-handler unit adapted to store events in the event queue sorted inan order of the time instant associated with each event.
 8. The radiocircuit according to claim 7, wherein the event-scheduling unitcomprises: a first-in/first-out memory operatively connected to theinterface unit for receiving event-request commands from the digitalbaseband circuit; and an event-dispatcher unit arranged to retrieveevent-request commands from the first-in/first-out memory and, for eachretrieved event-request command, forward an event associated with theevent-request command to one of the event handler units based on addressinformation in the event-request command.
 9. The radio circuit accordingto claim 1, wherein the event-scheduling unit is adapted to receiveevent-request commands comprising data associated with the eventspecified by the event-request command.
 10. The radio circuit accordingto claim 1, wherein a set of events that the radio circuit is adapted toexecute comprises one or more of a reconfiguration event forreconfiguring a hardware unit in the radio circuit, a measurement eventfor measuring a state of a hardware unit in the radio circuit, ameasurement data receive event for receiving measurement data generatedduring a measurement event, a power-down event, a power-up event, asleep event, a wake-up event, a calibration event for calibrating ahardware unit in the radio circuit, a data-transmission event, a resetevent for restoring a setting of the radio circuit to a default setting,and a debugging event.
 11. The radio circuit (20) according to claim 1,wherein the radio circuit is adapted to send event-request commands tothe digital baseband circuit for requesting events to be executed in thedigital baseband circuit.
 12. A communication circuit comprising a radiocircuit (20) according to claim 1 and a digital baseband circuit,wherein the digital baseband circuit comprises a time reference unit andis adapted to issue and send event-request commands to the radiocircuit.
 13. The communication circuit according to claim 12, whereinthe digital baseband circuit is arranged to: receive event-requestcommands from the radio circuit, wherein each event request commandspecifies an event to be executed in the digital baseband circuit and atime instant at which the specified event is to be executed; in responseto receiving an event request-command, schedule the specified event tobe executed on the specified time instant; and execute each scheduledevent at the scheduled time instant based on time information from thetime-reference unit of the digital baseband circuit.
 14. An electronicapparatus comprising a radio circuit according to claim
 1. 15. Theelectronic apparatus according to claim 14, wherein the electronicapparatus is a portable radio communication equipment, a mobile radioterminal, a mobile telephone, a communicator, an electronic organizer, asmartphone, or a computer.
 16. A method of operating a radio circuit,comprising: synchronizing a local time-reference unit of the radiocircuit with a time-reference unit in a digital baseband circuit inresponse to a synchronization command; receiving event-request commands,wherein each event-request command specifies an event to be executed inthe radio circuit and a time instant at which the specified event is tobe executed, from the digital baseband circuit; scheduling, in responseto receiving an event request-command, the specified event to beexecuted on the specified time instant; and executing each scheduledevent at the scheduled time instant based on time information from thelocal time reference unit.
 17. A computer program product comprisingcomputer program code means for executing a method when said computerprogram code means are run by an electronic device having computercapabilities, wherein the method is a method of operating a radiocircuit, comprising: synchronizing a local time-reference unit of theradio circuit with a time-reference unit in a digital baseband circuitin response to a synchronization command; receiving event-requestcommands, wherein each event-request command specifies an event to beexecuted in the radio circuit and a time instant at which the specifiedevent is to be executed, from the digital baseband circuit; scheduling,in response to receiving an event request-command, the specified eventto be executed on the specified time instant; and executing eachscheduled event at the scheduled time instant based on time informationfrom the local time reference unit.
 18. A computer readable mediumhaving stored thereon a computer program product comprising computerprogram code means for executing a method when said computer programcode means are run by an electronic device having computer capabilities,wherein the method is a method of operating a radio circuit, comprising:synchronizing a local time-reference unit of the radio circuit with atime-reference unit in a digital baseband circuit in response to asynchronization command; receiving event-request commands, wherein eachevent-request command specifies an event to be executed in the radiocircuit and a time instant at which the specified event is to beexecuted, from the digital baseband circuit; scheduling, in response toreceiving an event request-command, the specified event to be executedon the specified time instant; and executing each scheduled event at thescheduled time instant based on time information from the local timereference unit.
 19. The radio circuit according to claim 1, wherein thesynchronization unit is adapted to synchronize the local time-referenceunit with the time-reference unit in the digital baseband circuit inresponse to the synchronization command taking into account a latency ofthe communication link between the digital baseband circuit and theradio circuit.
 20. The method according to claim 16, whereinsynchronizing the local time-reference unit of the radio circuit withthe time-reference unit in the digital baseband circuit in response tothe synchronization command comprises synchronizing the localtime-reference unit of the radio circuit with the time-reference unit inthe digital baseband circuit taking into account a latency of acommunication link between the digital baseband circuit and the radiocircuit.